Diesel engines -- Clamp mounted CR fuel injectors -- Mounting dimensions

ISO 12251 specifies dimensional requirements for clamp mounted CR fuel injectors and their corresponding cylinder head features in diesel engines. According to the injector nozzle capnut, the clamp mounted CR fuel injectors can be divided into two types: a) Type A, where the nozzle capnut is straight (see Figure 4); b) Type B, where the nozzle capnut is stepped (see Figure 5). Each clamp mounted CR fuel injector type is subdivided by a series of different sizes. NOTE This differentiation corresponds to the relationship between the two guide diameters of the clamp mounted CR fuel injectors.

Moteurs diesels -- Injecteurs de combustible pour rampe commune fixée par patte -- Dimensions de montage

General Information

Status
Published
Publication Date
03-Oct-2017
Current Stage
6060 - International Standard published
Start Date
22-Aug-2017
Completion Date
04-Oct-2017
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INTERNATIONAL ISO
STANDARD 12251
Second edition
2017-09
Diesel engines — Clamp mounted CR
fuel injectors — Mounting dimensions
Moteurs diesels — Injecteurs de combustible pour rampe commune
fixée par patte — Dimensions de montage
Reference number
ISO 12251:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 12251:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

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ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 12251:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and symbols ............................................................................................................................................................ 1

4 General requirements ..................................................................................................................................................................................... 3

4.1 Clamp mounting arrangement .................................................................................................................................................. 3

4.2 Injector guiding dimensions........................................................................................................................................................ 4

4.3 Concentricity of the nozzle shaft ............................................................................................................................................. 4

4.4 High pressure connector ................................................................................................................................................................ 5

5 Dimensions and tolerances ....................................................................................................................................................................... 6

5.1 Type A, clamp mounted CR fuel injectors with straight capnut ................................................................... 6

5.2 Type B, clamp mounted CR fuel injectors with stepped capnut ................................................................... 8

6 Other specifications .......................................................................................................................................................................................10

7 Designation .............................................................................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................11

© ISO 2017 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 12251:2017(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by ISO/TC 22 Road Vehicles, Subcommitee SC 34 Propulsion, powertrain,

and powertrain fluids.

This second edition cancels and replaces (ISO 12251:2011) which has been technically revised.

The main changes compared to the previous edition are as follows:
— surface specification has been referenced to ISO 1302;
— ISO 2974 has been added for the high pressure connector;

— large D and small d have been interchanged, corresponding to ISO 286-1 (large D for bores, small d

for shafts);

— numbering D to D and d to d has been rearranged: same numbers now indicate same position

1 5 1 5
within the assembly of injector and cylinder head;

— Figure 5 has been completed in order to show the complete assembly and a new dimension D and

bore for capnut space have been added;

— D has been corrected to 24,1 in Table 2 at type A.5 (error in the first edition);

— Table 3 has been changed: tolerances for d changed to max. values and max. value for type B.2

changed from 19,1 to 19,2;
— dimension D and bore for capnut space 19,3 mm have been introduced in Table 4;
— type B.6 has been added in Table 3 and Table 4;
— Bibliography has been added.
iv © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 12251:2017(E)
Diesel engines — Clamp mounted CR fuel injectors —
Mounting dimensions
1 Scope

This document specifies dimensional requirements for clamp mounted CR fuel injectors and their

corresponding cylinder head features in diesel engines.

According to the injector nozzle capnut, the clamp mounted CR fuel injectors can be divided into

two types:
a) Type A, where the nozzle capnut is straight (see Figure 4);
b) Type B, where the nozzle capnut is stepped (see Figure 5).

Each clamp mounted CR fuel injector type is subdivided by a series of different sizes.

NOTE This differentiation corresponds to the relationship between the two guide diameters of the clamp

mounted CR fuel injectors.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 1302, Geometrical Product Specifications (GPS) — Indication of surface texture in technical product

documentation

ISO 2974, Diesel engines — 60 female cones for high pressure fuel injection components

3 Terms, definitions and symbols
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
For the purposes of this document, the following symbols apply:
d injector upper guide diameter
d injector shaft diameter
d capnut diameter
d injector lower guide diameter
d injector nozzle shaft diameter
D bore for upper guide diameter
© ISO 2017 – All rights reserved 1
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ISO 12251:2017(E)
D bore for capnut space
D bore for lower guide diameter
D bore for nozzle shaft
l overa
...

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